The news: Scientists have developed a new method for fighting cancer that involves unleashing killer stem cells specially created to fight the disease.

A team of researchers from Massachusetts General Hospital and the Harvard Stem Cell Institute have successfully tested the method on mice and published the findings in the journal Stem Cells. By engineering stem cells to secrete a toxin that kills cancer cells, they were able to remove brain cancer from the mice without harming any healthy cells.

"Cancer-killing toxins have been used with great success in a variety of blood cancers, but they don't work as well in solid tumours because the cancers aren't as accessible and the toxins have a short half-life," lead author Khalid Shah told BBC News. "Now, we have toxin-resistant stem cells that can make and release cancer-killing drugs."

In other words, if this method proves successful, doctors may actually be able to target cancer cells — and only cancer cells — to destroy them while leaving others unharmed, which would be a major revolution in the field of cancer treatment.

How it works: The researchers first took mice with brain cancer and surgically removed their tumors. They then extracted the genetically engineered stem cells, which were placed at the former tumor site in the form of a gel.

Because the stem cells were designed to produce a toxin that kills cancer cells, the big challenge was making sure the toxin didn't kill healthy brain cells or other stem cells. Luckily, this part was a success, and this success is what makes this potential treatment method so exciting.

The next step, Shah said, is to try the process using different types of cancers. He told BBC News he hopes there can be clinical trials in the next five years.

What it means: This doesn't mean we can now cure brain cancer, since the technique has yet to be tested on humans and will likely require plenty of work before it can be used outside of a laboratory environment.

Still, this is good news. The deadly and complex disease that it is, finding any new and promising method to fight cancer is always a step in the right direction. And from the initial findings of this stem cell treatment method, experts are calling this a major step in cancer treatment research.

"This is a clever study, which signals the beginning of the next wave of therapies," Chris Mason, professor of regenerative medicine at University College London, told BBC News. "Cells can do so much. This is the way the future is going to be."